There has been considerable interest in the detergent industry in the development of cleaning compositions having a relatively high bulk density, typically 500 g/l and above. Such high bulk density compositions are of interest in industry as they facilitate the production of detergent compositions having a low dosage volume, with the associated conservation of resources.
In general there are two main types of process by which detergent granules or powders are prepared. The first involves spray-drying an aqueous detergent slurry in a spray-drying tower, wherein the detergent active is dried by atomising it and spraying it into a stream of air at a high temperature. There has been considerable research and development into spray-drying process for the production of detergent compositions, for example, see the processes described in EP 360275, GB 2231579, WO 99/19453 and U.S. Pat. No. 4,524,010.
The second type of process involves dry mixing the detergent components, and subsequently agglomerating the dry-mixed components in high or medium speed mixer/densifier, typically in the presence of a liquid binder, such as water, a non-ionic or an anionic surfactant.
In practice spray-dried detergent compositions have been found to have relatively low bulk density. Spray-drying processes require expensive and complicated machinery and involve relatively high energy consumption. Furthermore, spray-drying processes typically result in the production of fine particles of the detergent composition, with the associated problems with regard to air pollution.
Detergent compositions having medium to high bulk densities have been produced by dry-mix agglomeration processes. However detergents produced by such dry-mix processes have been found to suffer from a number of problems, including poor dispersion properties and unsatisfactory detergent performance, as discussed in U.S. Pat. No. 6,303,558. Dry-mix processes also require the use of hi-tech mixer/densifier equipment.
Accordingly, there remains a need for alternative processes for the production of granular cleaning compositions having a relatively high bulk density. Also, there remains a need for such a process which is efficient and economical to facilitate large-scale production of granular cleaning compositions having a relatively high bulk density.
The inventors of the present Application have found that granular cleaning compositions having a relatively high bulk density may be prepared by a process involving adding water-soluble salts to an aqueous solution of a surfactant compound. The process disclosed herein allows the preparation of a granular cleaning composition without the requirement for expensive spray-drying or mixer/densifier equipment.